wijmo.angular2.core is an external TypeScript module that can be imported to your code using its ambient module name. For example:

import * as wjCore from 'wijmo/wijmo.angular2.core';
 
@Component({
    directives: [wjCore.WjTooltip],
    template: '<span [wjTooltip]="'Greeting'">Hello</span>',
    selector: 'my-cmp',
})
export class MyCmp {
}